As is known, scraper-chain conveyors, as used in mining, for example, usually employ a scraper-chain assembly with a series of scrapers attached to one or more chains. The scraper-chain assembly is then circulated along the pans of the conveyor to transport material along the conveyor from end to end. Each scraper is detachably connected to the chain or chains of the assembly with some form of fastening means so that the scrapers and their associated fastening means collectively form scraper units.
One form of scraper unit is described in GB-2077215. In this known design, the scraper-chain assembly has a pair of central chains and the scraper units are composed of scrapers and clamping straps. The scrapers each have vertical flange plates on either side of a pocket for receiving chain links and these flange plates are machined with bores. The clamping strap is also provided with pockets for receiving the chain links so that the links are trapped between the clamping strap and the scraper. The clamping strap has plate portions with bores which align with the bores in the flange plates of the associated scraper. Bolts fit through the aligned bores and nuts are tightened onto the bolts to secure the strap to the scraper. The flanges of the scrapers and the plates of the strap have inter-engaging faces. Either these faces are offset from the vertical or else the bores are inclined to the floor plates of the conveyor pans to create an upwardly directed force as the nuts are tightened on the bolts to draw the strap towards the scraper and firmly secure the chain links in the pockets. The special shaping of the components which make up the known scraper unit involves high manufacturing costs. Moreover, the nuts and bolts tend to slacken off during use and the resultant play of the chain links causes heavy wear to the pockets.
A general object of the invention is to provide a scraper unit of improved design and performance.